Recently, a chemical heat storage device has been known as a heater for a vehicle, an architectural structure, or outdoors. For example, in an electric vehicle (EV) which travels using a motor without an engine being mounted on, it is difficult to use heat release of cooling water of an engine as heat for air heating, unlike in a case of a vehicle with an engine driving system. As a heater device usable in such a case, devices (chemical heat storage devices) which use chemical heat storage are disclosed in JP 11-182968A and JP 2010-216772A (References 1 and 2). A chemical heat storage material reacts with a reaction medium to generate heat and a reaction product. Since this reaction is reversible reaction, the chemical heat storage material can be regenerated. In detail, if the reaction medium is water, the chemical heat storage material can be regenerated by heating and dehydration reaction of the reaction product. Hereinafter, regeneration of the chemical heat storage material by heating the reaction product is called heating and regenerating of the chemical heat storage material, if necessary. In addition, generation of heat and the reaction product by reaction of the chemical heat storage material and the reaction medium is called heat generation of the chemical heat storage material.
In a technology disclosed in JP 11-182968A, by providing an electric heater to the outside of a heat storage material accommodation unit which performs reaction of the reaction medium and the chemical heat storage material, the reaction product accommodated in a reaction unit is heated. According to the technology, it is possible to perform heating and regenerating of the chemical heat storage material, however, on the other hand, since the entire heat storage material accommodation unit is heated, efficiency of heating and regenerating of the chemical heat storage material is degraded. That is, in the chemical heat storage device disclosed in JP 11-182968 A, by heating a heater, the reaction unit which is adhered to the heater is indirectly heated. Further, the reaction product in the reaction unit is indirectly heated. Accordingly, in this chemical heat storage device, problems with great heat-transfer loss at the time of heating and regenerating of the chemical heat storage material and degraded heat efficiency at the time of heating and regenerating of the chemical heat storage material.
In a technology disclosed in JP 2010-216772A, a cell obtained by concentrating chemical heat storage materials is manufactured, a flow path is provided in the cell, and fluid with a high temperature flows through the flow path, and thus, a reaction product is heated. By diverting this technology, if a transfer flow path (for example, a flow path of fluid in a case of heating the chemical heat storage material with fluid, hereinafter, called a heat transfer unit, not otherwise specified) of heat is provided in a heat storage material accommodation unit to directly perform heating and regenerating of the chemical heat storage material, it is considered that it is possible to reduce heat-transfer loss at the time of heating and regenerating of the chemical heat storage material, (that is, it is possible to efficiently perform heating and regenerating of the chemical heat storage material), and efficiency of heating and regenerating of the chemical heat storage material is improved.
However, when a plurality of heat transfer units are provided in the heat storage material accommodation unit for transfer of heat in the heat storage material accommodation unit, the chemical heat storage material is interposed between the adjacent heat transfer units. Since the chemical heat storage material is expanded at the time of reaction with the reaction medium (that is, the time of heat generation), the chemical heat storage material which is interposed between the heat transfer units is compressed, and aggregation and solidification thereof between the heat transfer units may occur. Heat is difficult to be transferred to or the reaction medium is difficult to be brought in contact with the center portion of the aggregated/solidified chemical heat storage material. Accordingly, the center portion of the solidified chemical heat storage material is difficult to be used in a cycle of heat generation→heating and regenerating, and as a result, a reaction rate or a reaction speed of the chemical heat storage material may be decreased. That is, the plurality of heat transfer units are provided in the heat storage material accommodation unit for improving the efficiency of heating and regenerating of the chemical heat storage material, however, in practice, the efficiency of the heat generation of the chemical heat storage material and the efficiency of the heating and regenerating of the chemical heat storage material may be degraded because of that.
In addition, if the solidified chemical heat storage material is stuck between the heat transfer units, when replacing the chemical heat storage material of the accommodation unit after a long-term use, a replacement operation is complicated, in some cases.
As described above, in the chemical heat storage device of the related art disclosed in JP 11-182968A and JP 2010-216772A, a mechanism for heating and regenerating of the chemical heat storage material is insufficient, and it is difficult to sufficiently improve the efficiency of heating and regenerating of the chemical heat storage material and the efficiency of heat generation of the chemical heat storage material. In detail, it was difficult to suppress aggregation/solidification of the chemical heat storage material and to efficiently perform heating and regenerating of the chemical heat storage material.
A need thus exists for a chemical heat storage device which is not susceptible to the drawback mentioned above.